SM 25x275 [2xM8] / N42 - magnetic separator

Advantages and disadvantages of neodymium magnets NdFeB.

Apart from their notable power, neodymium magnets have these key benefits:

• They retain their attractive force for around 10 years – the loss is just ~1% (in theory),
• They remain magnetized despite exposure to magnetic surroundings,
• In other words, due to the glossy gold coating, the magnet obtains an professional appearance,
• They possess intense magnetic force measurable at the magnet’s surface,
• They are suitable for high-temperature applications, operating effectively at 230°C+ due to advanced heat resistance and form-specific properties,
• With the option for customized forming and personalized design, these magnets can be produced in multiple shapes and sizes, greatly improving application potential,
• Important function in modern technologies – they are used in HDDs, electric motors, healthcare devices or even high-tech tools,
• Thanks to their efficiency per volume, small magnets offer high magnetic performance, with minimal size,

Disadvantages of magnetic elements:

• They are fragile when subjected to a strong impact. If the magnets are exposed to mechanical hits, we recommend in a protective enclosure. The steel housing, in the form of a holder, protects the magnet from breakage and increases its overall strength,
• They lose magnetic force at high temperatures. Most neodymium magnets experience permanent degradation in strength when heated above 80°C (depending on the dimensions and height). However, we offer special variants with high temperature resistance that can operate up to 230°C or higher,
• Magnets exposed to damp air can rust. Therefore, for outdoor applications, we suggest waterproof types made of plastic,
• Limited ability to create precision features in the magnet – the use of a external casing is recommended,
• Possible threat linked to microscopic shards may arise, when consumed by mistake, which is important in the health of young users. Moreover, small elements from these assemblies can disrupt scanning if inside the body,
• Due to the price of neodymium, their cost is considerably higher,

Highest magnetic holding force – what affects it?

The given holding capacity of the magnet means the highest holding force, assessed in ideal conditions, namely:

• using a steel plate with low carbon content, acting as a magnetic circuit closure
• with a thickness of minimum 10 mm
• with a polished side
• with no separation
• with vertical force applied
• at room temperature

Determinants of lifting force in real conditions

In practice, the holding capacity of a magnet is conditioned by these factors, arranged from the most important to the least relevant:

• Air gap between the magnet and the plate, as even a very small distance (e.g. 0.5 mm) can cause a drop in lifting force of up to 50%.
• Direction of applied force, because the maximum lifting capacity is achieved under perpendicular application. The force required to slide the magnet along the plate is usually several times lower.
• Thickness of the plate, as a plate that is too thin causes part of the magnetic flux not to be used and to remain wasted in the air.
• Material of the plate, because higher carbon content lowers holding force, while higher iron content increases it. The best choice is steel with high magnetic permeability and high saturation induction.
• Surface of the plate, because the more smooth and polished it is, the better the contact and consequently the greater the magnetic saturation.
• Operating temperature, since all permanent magnets have a negative temperature coefficient. This means that at high temperatures they are weaker, while at sub-zero temperatures they become slightly stronger.

* Lifting capacity was determined using a polished steel plate of suitable thickness (min. 20 mm), under vertically applied force, in contrast under parallel forces the holding force is lower. Additionally, even a small distance {between} the magnet’s surface and the plate decreases the holding force.